Laser reactive dyes for DVD copy protection system

ABSTRACT

A method and system for providing copy-protected optical medium using transient optical state change security materials capable of changing optical state when exposed to a wavelength of about 630 nm to about 660 nm and software code to detect such change in optical state.

RELATED APPLICATIONS

[0001] This application is a continuation-in-part application of U.S.patent application Ser. No. 10/418,898 which claims priority to U.S.Provisional Patent Application Nos. 60/389,223 filed Jun. 17, 2002,60/390,647 filed Jun. 21, 2002, 60/391,773 filed Jun. 25, 2002,60/391,857 filed Jun. 26, 2002, and 60/393,397 filed Jul. 2, 2002, thedisclosure of each which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention generally relates to transient opticalstate change security materials reactive to a wavelength of about 630 nmto about 660 nm, in particular to wavelengths produced by DVD opticalreaders. Such materials may be used by directed application to opticalmedium to effectuate copy-protection. More specifically, the materialsmay be used to manufacture optically readable digital storage mediumthat protects the information stored thereon from being copied usingconventional optical medium readers, but permits reading of theinformation from the digital storage media by the same readers.

[0004] 2. Description of the Related Art

[0005] Data is stored on optical media in the form of opticaldeformations or marks placed at discrete locations in one or more layersof the medium. Such deformations or marks effectuate changes in lightreflectivity. To read the data on an optical medium, an optical mediumplayer or reader is used. An optical medium player or readerconventionally shines a small spot of laser light, the “readout” spot,through the disc substrate onto the data layer containing such opticaldeformations or marks as the medium or laser head rotates. Two commontypes of optical media are the CD disc, providing a maximum storagespace of about 650 megabytes of data on a single-side (SS), single-layer(SL) disc, and the DVD disc providing about 4.37 GB (1GB=2³¹ bytes) on asingle-sided (SS), single-layer (SL) disc. The ECMA Technical CommitteeTC31 was established in 1984 for the standardization of Optical Discsand Optical Disc Cartridges, making contributions to ISO/IEC SC23 withrespect to International Standards.

[0006] The vast majority of commercially-available software, video,audio, and entertainment pieces available today are recorded inread-only optical format. One reason for this is that data replicationonto read-only optical formats is significantly cheaper than datareplication onto writable and rewritable optical formats. Another reasonis that read-only formats are less problematic from a readingreliability standpoint. For example, some CD readers/players havetrouble reading CD-R media, which has a lower reflectivity, and thusrequires a higher-powered reading laser, or one that is better “tuned”to a specific wavelength.

[0007] In conventional “read-only” type optical media (e.g., “CD-ROM”),data is generally encoded by a series of pits and lands that aremetallized. A readout spot directed from the non-metallized side isreflected in a manner that the light of readout spot is reflected backinto a photosensor in the reader. When referenced from the laser readingside, pits are technically referred to as bumps. The transitions betweenpits and lands, and the timing in between such transitions, representchannel bits. Thus the pit and lands in themselves are notrepresentations of a sequence of zeros or ones. Typically, in CDs 14channel bits make up a data symbol that translates to an 8 bit datavalue, in a process referred to as 8 to 14 modulation (EFM). DVD uses amodified version of EFM, known as EFM+ to convert 8-bit data directlyinto 16 channel bits. The NRZI (non-return to zero inverted) waveformrepresentation is used to interpret the binary sequence on the disc.

[0008] Microscopic pits formed in the surface of the plastic medium arearranged in tracks, conventionally spaced radially from the center hubin a spiral track originating at the medium center hub and ending towardthe medium's outer rim. The pitted side of the medium is conventionallycoated with a reflectance layer such as a thin layer of aluminum orgold. The “pits” as seen from the metallized side, are also referred to“bumps” when referencing view from the laser-read side. A lacquer layeris typically coated on the pit side as a protective layer.

[0009] The intensity of the light reflected from a read-only medium'ssurface measured by an optical medium player or reader varies accordingto the presence or absence of pits along the information track. Asdefect-induced errors may interfere with read, all optical discs employerror management strategies to eliminate the effect of such errors.

[0010] The optical reader, such as the CD or DVD reader, has the job offinding and reading the data stored as bumps on the disc. In aconventional player a drive motor spins the disc. A laser and lenssystem focus light on the bumps, and an optical pickup head (PUH)receives reflected light. A tracking mechanism moves the laser assemblyso that the laser's beam can follow the spiral track, conventionallymoving the laser outward from the center as the disc is played. As thelaser moves outward from the center of the disc, the bumps move past thelaser faster, as the speed of the bumps is equal to the radius times thespeed at which the disc is revolving (rpm). A spindle motor isconventionally employed to slow the speed of the disc when the laser isreading further and further out from the center of the disc permittingthe laser to read at a constant speed, such that the data is read fromthe disc at a constant speed.

[0011] The semiconductor laser utilized, the spread of its wavelength,and its operational temperature affect the wavelength read by the pickup head (PUH) of the reader. DVD readers presently utilize lasers thatproduce a wavelength of about 630 to about 660 nm, with standard DVDreaders measuring a wavelength of 650±5 nm and standard DVD-R readersmeasuring a wavelength of 650 +10/−5 nm. As would be understood by oneof skill in the art, the PUHs can detect only those reflected beams thatfall within a certain angular deviation from the incident beam. Forexample, a typical DVD-R requires that the radial deviation be no morethan ±0.80° and tangential deviation no more than ±0.30°.

[0012] Optical media of all types have greatly reduced the manufacturingcosts involved in selling content such as software, video and audioworks, and games, due to their small size and the relatively inexpensiveamount of resources involved in their production. They have alsounfortunately improved the economics of the pirate, and in some media,such as video and audio, have permitted significantly betterpirated-copies to be sold to the general public than permitted withother data storage media. Media distributors report the loss of billionsof dollars of potential sales due to high quality copies.

[0013] Typically, a pirate makes an optical master by extracting logicdata from the optical medium, copying it onto a magnetic tape, andsetting the tape on a mastering apparatus. Pirates also sometimes use CDor DVD recordable medium duplicator equipment to make copies of adistributed medium, which duplicated copies can be sold directly or usedas pre-masters for creating a new glass master for replication. Hundredsof thousands of pirated optical media can be pressed from a singlemaster with no degradation in the quality of the information stored onthe optical media. As consumer demand for optical media remains high,and because such medium is easily reproduced at a low cost,counterfeiting has become prevalent.

[0014] WO 02/03386 A2, which asserts common inventors to the presentapplication, discloses methods for preventing copying of data from anoptical storage media by detecting optical dis-uniformities or changeson the disc, and/or changes in readout signal upon re-reading of aparticular area on the optical storage medium, in particular thosecaused by light-sensitive materials, such as dyes, which may affect thereadout wavelength by absorbing, reflecting, refracting or otherwiseaffecting the incident beam. Software control may be used to deny accessto content if the dis-uniformity or change in read signal is notdetected at the position on the disc wherein the dis-uniformity orchange is anticipated. The disclosure of WO 02/03386 A2 is incorporatedherein in its entirety by reference.

[0015] A preferred embodiment described in publication WO 02/03386 A2comprises light-sensitive materials are optically-changeable securitymaterials that are positioned upon the optical disc in a manner thatthey do not adversely affect the data-read of the readout signal in oneoptical state but upon exposure to the wavelength of the optical readerincident beam covert to a second optical state, preferably in atime-delayed fashion, that does affect the data-read of the readoutsignal. In a preferred embodiment described in WO 02/03386 A2, theoptically-changeable security material only transiently changes opticalstate and its optical state reverts over time.

[0016] It has been discovered by the present inventors that the optimalcharacteristics for such preferred transient optically-changeablesecurity materials described in publication WO 02/03386 A2 depend upon anumber of factors, including, the characteristics of the incident beamgenerated by the laser reader used (such as the beam intensity andwavelength), the particular materials used to fabricate the optical discin particular with respect to the optical characteristics of suchmaterials with respect to the reading beam (such as refractive index andbirefringence), the particular formatting of the disc (such as pitdepth), where the optically-changeable security material is positionedon or within the disc (e.g., on the surface versus in a layer of thedisc/in the data section of the disc versus), the opticalcharacteristics of other materials that may be introduced to effectuateincorporation of the optically-changeable security material onto or intothe disc, the characteristics of the pickup head (PUH) of the opticalreader in particular with respect to readout wavelength and angle ofdeviation permitted for pickup of reflected light emanating from theincident beam, the reading characteristics of the optical reader systemin particular related to scan velocity, the time for re-scan, androtational speed of the disc. For example, the material should notchange state too quickly so as not to allow the PUH to observe bothstates. On the other hand, it should not change state too slowly so asto eventuate in a disc that would take non-commercially acceptable timesfor validation of the disc and read.

[0017] An optimal transient optical state change security materialshould be thermally and photochemically stable under conditions ofoptical use and at ambient conditions for a significant period of time.It should be soluble in a matrix that comprises the disc, or that can beadheredly-applied to the disc. An optimal transient optical state changesecurity material should revert to its state without the need forextraneous inputs of energy, and should demonstrate a change in opticalstate at the incident wavelength of the reader.

[0018] There is a need for optical state change security materials thatmay be employed in a manner described in WO 02/03386 A2 to effectuatecopy-protection of optical discs, in particular DVDs, that conform toISO/IEC standards when read by their respective ISO/IEC standardizedreaders. In particular there is a need for identifying materials thatmay be used in such copy protection methodologies without requiringmodification to optical medium readers.

DEFINITIONS

[0019] “Data Deformation”: a structural perturbation on or in an itemthat represents stored data and can be read by an optical reader.

[0020] “Dye”: an organic material detectable by optical means.

[0021] “Fabry-Perot Interferometer”: an Interferometer making use ofmultiple reflections between two closely spaced reflective surfaces, andtypically has a resolvance of λ/Δλ=m r/1−r

[0022] “Interferometer”: a device employing two or more reflectivesurfaces to split a beam of light coming from a single source into twoor more light beams which are later combined so as to interfere in aconstructive or destructive manner with each other.

[0023] “Optical Medium”: a medium of any geometric shape (notnecessarily circular) that is capable of storing digital data that maybe read by an optical reader.

[0024] “Optical Reader”: a Reader (as defined below) for the reading ofOptical Medium.

[0025] “Optical State Change Security Material”: refers to an inorganicor organic material used to authenticate, identify or protect an OpticalMedium by changing optical state from a first optical state to a secondoptical state.

[0026] “Permanent Optical State Change Security Material”: refers to aTransient Optical State Change Security Material that undergoes changein optical state for more than thirty times upon read of the OpticalMedium by an Optical Reader.

[0027] “Reader”: any device capable of detecting data that has beenrecorded on an optical medium. By the term “reader” it is meant toinclude, without limitation, a player. Examples are CD and DVD readers.

[0028] “Read-only Optical Medium”: an Optical Medium that has digitaldata represented in a series of pits and lands.

[0029] “Recording Layer”: a section of an optical medium where the datais recorded for reading, playing or uploading to a computer. Such datamay include software programs, software data, audio files and videofiles.

[0030] “Re-read”: reading a portion of the data recorded on a mediumafter it has been initially read.

[0031] “Transient Optical State Change Security Material”: refers to aninorganic or organic material used to authenticate, identify or protectan Optical Medium by transiently changing optical state between a firstoptical sate and a second optical state and that may undergo such changein optical state more than one time upon read of the Optical Medium byan Optical Reader in a manner detectable by such Optical Reader.

[0032] “Temporary Optical State Change Security Material”: refers to anOptical State Change Security Material that undergoes change in opticalstate for less than thirty times upon read of the Optical Medium by anOptical Reader.

[0033] For the purpose of the rest of the disclosure it is understoodthat the terms as defined above are intended whether such terms are inall initial cap, or not.

SUMMARY OF THE INVENTION

[0034] The present invention provides a for dyes and dye systems whichexhibit a reversible change in optical state which is detectable by areader upon exposure of such dyes and dye systems to a wavelength ofabout 630 to about 660 nm. In a preferred embodiment, such dyes and dyesystems act as transient optical state change security materials,providing for a change in optical state that can be repeated numeroustimes upon exposure to/and removal from such wavelength. That is, thepresent invention provides a method for ascertaining those compoundsdisplaying transient characteristics induced by exposure to read beam ofan optical reader such that the change can be detected by the uptakehead of the optical reader.

[0035] In one preferred dye system embodiment, the dye system on anoptical disc comprises: (1) a dye that rapidly changes optical statefrom a first unactivated optical state to a second activated opticalstate in response to a wavelength of about 630 to about 660 nm which isdetectable by the uptake head of an optical reader when the dye is inits second optical state, but not the dye is in its first optical state;(2) a dye-carrying polymer in which the dye is dispersed; and (3) amaterial that aids in reducing the reversal time of the dye from itssecond activated optical state back to its first unactivated opticalstate. Optionally such system may also comprise a material that aids inreducing the time to the second activated optical state from the firstunactivated optical state. The optical state change in any opticallymeasurable manner, for example in causing a change in reflection and/orrefraction, as long as the optical change can be detected. For example,in one embodiment the dye/dye system changes the percent reflectance onthe optical disc by approximately 25% to approximately 30% which hasbeen seen to be sufficient for detection at the pickup head.

[0036] One particularly useful class dyes capable of being activated bya wavelength of about 630 to about 660 nm that have been identified are:

[0037] where R₆, R₇, R₈, and R₉ are alkylamino and R₁, R₂, R₃, R₄ and R₅are selected from the group consisting of hydrogen, alkyl, aryl, alkoxy,thioalkoxy, alkylamino, nitro, amino and halogen. In one preferredembodiment R₆, R₇, R₈, and R₉ are each, or independently, propyl orhexyl and R₁, R₂, R₃, R₄ and R₅ are hydrogen or alkyl.

[0038] Such dye substances can be incorporated into a dye system whichcomprises an electron donor agent (ED)/electron transfer agent (ETA).Such compounds are electron rich and provide electrons to the dyemolecule for example once the dye molecule is reduced to thecorresponding leuco form. In the presence of laser light, thisphenomenon may be referred to as photoreduction.

[0039] Non-limiting examples of ETAs which may be incorporated into thedye system include triethanol amine, diethanol amine, TMG, DMEA, DEMEA,TMED, EDTA, Bis-Tris, p-tolylimido diethanol, N-tert-butyldiethanolamine, 4-morpholine ethanol, 1,4-bis-2-hydroxyethyl piperazine, bicineand BES.

[0040] The ETA may be incorporated into the polymeric base of a dyesystem physically or chemically. For example, a useful ETA may be boundto the repeating polymeric unit. For example, a compound of thefollowing structure has been found to be a useful ETA: as well as othercompounds comprising a polymer having a bis(2-hydroxy ethyl) aminofunctionality. A preferred polymer may be in the molecular weight rangeof 50-100k.

[0041] Other non-oxygen associated ETAs may be used, such as acombination of reductants such as Fe (II)-Fe (III).

[0042] The dye and/or dye system may be used on an optical disc toeffectuate data changes on the disc, preferably at the bit level code.As described in the applications referenced above, a security softwarecan be sued to confirm the change in code. The dye/dye system ispreferably placed in a manner on the disc so as not to alter playabilityon industry compliant DVD devices.

[0043] As would be understood by one of ordinary skill in the art, thedyes/dye systems employed on an optical disc should be selected suchthat they do not decay or degrade and such they are safe.

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings, which are incorporated in andconstitute part of the specification, illustrate presently preferredembodiments of the invention, and together with the general descriptiongiven above and the detailed description of the preferred embodimentsgiven below, serve to explain the principles of the invention.

[0045]FIG. 1 illustrates a multi-layer optical disc embodiment of thepresent invention having reflective layer, dye layer, and transparentsubstrate;

[0046]FIG. 2 is a chart of reflectivity versus time in regard to a dyesystem unexposed to DVD reader laser light, exposed to DVD reader laserlight, and recovered from exposure to DVD reader laser light;

[0047]FIG. 3 is a real time plot of pit/land signal with respect to thedye system of FIG. 2;

[0048]FIG. 4 is an atomic force microscope photo of a multi-depth pitmaster which may be used to form a multi-depth pit disc; and

[0049]FIG. 5 is an atomic force microscope photo of a multi-depth pitdisc with dye/dye system of the present invention being coated on thehighest bumps (deepest pits).

DETAILED DESCRIPTION OF THE INVENTION

[0050] The present invention provides for transient transient opticalstate change security materials reactive to a wavelength of about 630 nmto about 660 nm, in particular to wavelengths produced by DVD opticalreaders. The transient optical state change security materials may beused to manufacture optically readable digital storage medium thatprotects the information stored thereon from being copied usingconventional optical medium readers, but permits reading of theinformation from the digital storage media by the same readers.

[0051] As disclosed in WO 02/03386 A2, which asserts common inventors tothe present application, transient optical state change securitymaterials may be used to effectuate copy-protection of an optical discby providing a change in optical state upon activation of the materialby the incident reading laser beam, that is of such character that upona second read of the area of the disc where the transient optical statechange security material is located a change in data read is detected atthe optical pickup head. The materials may be used to cause anuncorrectable error upon re-read of such a character that the errorinterferes with copying function of most optical readers that requireoversampling in the copying process, and/or a uncorrectable/correctableerror, or a change in interpretation of a data read, that due to analgorithm on the disc, which may be incorporated as an encryption code,and/or an algorithm incorporated into the reader and/or componentassociated with the reader, is used to authenticate the disc and permitcopying only upon authentication.

[0052] The materials may also be used to effectuate complementary datasequences (CDSs) both of which are interpreted as valid, both of whichare interpreted as erroneous, or one of which is interpreted as validand the other as erroneous, or one of which is interpreted as erroneousand the other as valid. That is, the for example, the materials may beused to cause a pit to disappear altogether of change its length becausepart of it disappeared. It is preferred that the material be conformalwith the data structure. Copy protection may be effected using CDSs by,for example, having the first valid data read attributable to thematerial in its unactivated state directing the reader to an erroneoustrack on the disc, while having the second valid data read attributableto the material in its activated state directing the reader to thecorrect track for further effectuating of the read. As would beunderstood, copying of the disc in such situation is hampered byresampling by the copying device (which reads two different valid datareads). When such error is detected, re-seek algorithms internal to thedrive will cause the data stored in the tracking control to be re-read.If the transient optical state change security material, which may betemporary or permanent, is in its second state, and the second state isselected as to allow the underlying data to be read, the new addresswill be correct and the content on the disc will be able to be read. Inone embodiment of such “spoofing” technique for copy-protection, thematerial is placed at the subcode level in the lead-in zone thuseffecting the table of contents. The material may be placed at themicrolevel in the CRC field. A copy of the disc incorporating datahaving the first valid data read alone would not work due to the failureof the data to direct subsequent reading to the correct track. Thetransient optical state change security material may also provide for avalid data state read in a first optical state, but an uncorrectableread error in a second optical state, making it significantly moredifficult for a would-be copier of the disc to reproduce an operabledisc by incorporating an uncorrectable error, such as a physicaldeformation, into the disc.

[0053] By “correctable error” it is meant an error which is correctableby the ECC used with respect to the optical disc system, while an“uncorrectable error” is an error which is not correctable. ECC arealgorithms that attempt to correct errors due to manufacturing defectssuch that the opticaldisc works as intended. Error detection methods areconventionally based on the concept of parity. All optical discs employerror management strategies to eliminate the effect of defect-inducederrors. It has been found that even with the most careful handling, itis difficult to consistently manufacture optical discs in which thedefect-induced error rate is less than 10⁻⁶. Optical recording systemsare typically designed to handle a bit-error rate in the range of 10⁻⁵to 10⁻⁴. The size of the defect influences the degree of errorassociated with the defect. Thus some defects create such a marginalsignal disturbance that the data are almost always decoded correctly.Slightly smaller defects might induce errors hardly ever. Macro or microdepositions may also be used to cause correctable or uncorrectableerrors. For example, micro depositions may be of such size as to kill adata group that is fixable by C₁/C₂ of ECC of a CD, but if applied tokill enough groups may cause an uncorrectable error detectable by suchsoftware.

[0054] The type of transient perturbation that is desired to beeffectuated, whether a correctable error, uncorrectable error, two ormore complementary valid data sequences, a valid data sequence and acorresponding invalid data sequence and/or other detectable change atthe optical pickup head, will dictate where on the disc the transientoptical state change security material will be placed. For example, if adata change detectable by the optical pickup head is desired, thematerial should not of course be placed in the clamping zone. If thereis a valid to valid, or erroneous to erroneous data state change, inorder to allow easy detection it is preferred that the data state changecauses a change in the values read. In error state to error statechanges the level of severity of the errors preferably is different,thereby aiding detectability.

[0055] The present invention discloses transient optical state changesecurity materials (both temporary optical state change securitymaterials, and permanent optical state change security materials) thatchange optical state upon exposure to a wavelength produced by DVDreaders. The material, which may comprise a dye or dye system,transiently changes the signal read by the pickup head by changing, forexample the reflectivity of the laser beam when the material is in itsactivated state versus its unactivated state. Typically, when used forthe production of copy protected optical discs, the dye acts to change adetectable parameter, e.g. reflectivity, at a few selected pit/landstructures. A typical dye system comprises a dye which changes from afirst unactivated optical state to a second activated optical state uponexposure to a wavelength produced by a DVD reader, e.g. form about 630nm to about 660 nm, a electron donor agent or electron transfer agentwhich aids in the conversion of the activated second optical state backto the unactivated first optical state, and a polymer. It has been foundthat the system composition affects the laser activation, the rate andintensity of optical sate change in response to an activationwavelength, and the conformal application of the dye/electron donor tothe disc.

[0056] A DVD read laser has a spectra centered about 650 nm wavelength.The absorption spectra for methylene blue in solution shows anabsorption maxima at 655 nm. While such dye might appear to be useful initself as a transient optical state change material, when applied tooptical disc it was observed that the absorption underwent abathochromic shift with the spectrum having an absorption maxima atabout 590 nm due to aggregration. The absorption spectrum was of thecompound was found to be modifiable by altering the steric bulk on thenitrogen. A preferred structure in regard to a a methylene blue backbonecomprised improved electron withdrawal at the positively charged sidechain nitrogen, and electron withdrawal at the other side chainnitrogen.

[0057] One particularly useful class dyes capable of being activated bya wavelength of about 630 to about 660 nm that have been identified are:

[0058] where R₆, R₇, R₈, and R₉ are alkylamino and R₁, R₂, R₃, R₄ and R₅are selected from the group consisting of hydrogen, alkyl, aryl, alkoxy,thioalkoxy, alkylamino, nitro, amino and halogen. In one preferredembodiment R₆, R₇, R₈, and R₉ are each, or independently, propyl orhexyl and R₁, R₂, R₃, R₄ and R₅ are hydrogen or alkyl.

[0059] Preparation of Exemplar Thiazine Compounds Useful forCopy-Protected DVDs

EXAMPLE 1 Propyl and Hexyl Analogs of Methylene Blue

[0060] To shift the absorption maxima closer to 650 nm, propyl (MB-3)and hexyl (MB-6) analogs of methylene blue were synthesized using theprocedure described by Mellish et al. as set forth below.

[0061] The absorption maxima of the compounds when coated onto opticalmedia was in the expected range and the change in optical state wasdetectable by the PUH. The optical density of 5% poly-HEMA(poly-2-hydroxyethyl methacrylate), 250 mg MB-3, and 160 mg Bis-Tris(2,2-Bis(hydroxymethyl)-2-2′,2″-nitroethanol) on one disc was 0.22absorbance units at 650 nm and the optical density on another disc using325 mg MB-3, 5% poly-HEMA and 160 mg Bis-Tris was 0.3 absorbance units.The disc with optical density of 0.22 absorbance units demonstratedabout a 18% photobleach at 650 nm. The disc with optical density 0.32absorbance units demonstrated about a 30% photobleach at 650 nm.

[0062] An ETA or ED (electron donor agent) is a compound that iselectron rich and provides electrons to the dye molecule that is beingreduced to the corresponding leuco form. In the presence of laser light,this phenomenon is called photoreduction:

[0063] ETAs are particularly useful in a dye system of the presentinvention when photoreduction is a principle means of optical statechange back to the unactivated state. ETA's that can be used in thissystem include, but not limited to, triethanol amine, diethanol amine,TMG, DMEA, DEMEA, TMED, EDTA, Bis-Tris, p-tolylimido diethanol,N-tert-butyldiethanol amine, 4-morpholine ethanol, 1,4-bis2-hydroxyethylpiperazine, bicine and BES. Such ETAs have been found to photobleach thesystem using a DVD laser on the pulsetec. In general percdentphotobleach observed was directly proportional to the amount of ETAadded in the system, but it was found that there is a limit to theamount of ETA that can be tolerated in the system after which discs arenot playable.

[0064] Preparation of Exemplar Copy-Protected DVD

EXAMPLE 2 Optical Disc Having Dye System Comprising MB-3

[0065] 250 mg of MB-3 dye was added to a 25 ml 4% polymer solution in1-methoxy 2-propanol Aldrich catalog No. 484407 and 150 mg of Bis-Triswas added. The resulting solution was stirred vigorously on a shaker for30-60 min. The final solution was filtered through a 0.2 μm filter andwas used to spin coat optical discs. The spin coater used for thispurpose was model P-6708D manufactured by Specialty Coating Systems.

EXAMPLE 3 Optical Disc Having Dye System Comprising MB-3

[0066] To a 25 ml solution of 4% PolyHEMA in methoxy propanol was added300 mg of MB-3 and 150 mg of Bis-Tris. The solution was stirred on ashaker for 30 min and filtered through 0.2 um filter and the filteredsolution was used to coat discs using a spin coater Disc No. 1854-1857.

[0067] A two component dye system is yet another embodiment of theinvention. In such system, the ETA is combined chemically with thepolymer. It has been found by the present inventors that polymers thathave ETA appended will photobleach. Useful electron transfer polymersinclude, but are not limited to: a) any polymer containing thebis(2-hydoxyethyl)amino functionality as shown below, b) homo-polymersor copolymers with vinyl acetate or methacrylate containing the(2-hydoxyethyl)amino functionality.

[0068] and c) any other polymer in Mol wt. range 50-100K that is solublein methoxy propanol and having a bis(2-hydroxy ethyl) aminofunctionality.

EXAMPLE 4 ETA Polymer-Methylene Blue Dye System

[0069] Polyethylenimine which was 80% ethoxylated in water was adjustedto a pH of about 8 using concentrated HCl and methylene blue added tobring the absorbance to 3. Photobleach of the system was seen with asimple overhead projector to be in the range of 2-3 seconds withoxidation back to unactivated state in approximately 2-3 minutes.

[0070] Combinations of reductants such as Fe (II)-Fe (III) can be usedfor an oxygen free system. For example, the catalytic effect of ferrousion on the photochemical bleaching of thionine in the presence ofdiethylallylthiourea is related to the present work on methylene blue.On irradiating a 0.001% aq. solution of thionine containing 0.0075 mol.per liter, the dye bleaches in 1-2 sec. The color returns again in 1-2sec. after removal of the light. Similarly the leuco form of the dyewill return to the original colored form in the presence of weak-strongoxidizing agents such as bromine or silver halides to name a few.

[0071] Now turning to the figures, FIG. 1 illustrates a cross-section ofan optical medium embodiment comprising a transient optical state changesecurity material between two substrates. FIG. 4 is an atomic forcemicroscope photo of a multi-depth pit master which may be used to form amulti-depth pit disc. Such multi-depth pit (i.e. heightened bump) may beuseful for easing application of the dye to select pits (bumps from theread side). FIG. 5 is an atomic force microscope photo of an exemplarmulti-depth pit disc with dye system of the present invention beingcoated on the highest bumps (deepest pits). FIG. 2 is a chart ofreflectivity versus time in regard to a dye system before and duringexposure to a DVD reader laser light, and after it has returned to theunactivated state. FIG. 3 is a real time plot of pit/land signal withrespect to the dye system of FIG. 2.

[0072] Optimization of transient optical state change security materialsfor a particular reader is influenced in part by the particularmaterials used to fabricate each layer of the optical disc itself, andthe material's position vis-a-vis such layers and the incident laserbeam. It is therefore useful when selecting for such optimal securitymaterials with respect to a particular reader that the material beplaced on a disc of similar fabrication and placed for testing purposesin a manner similar to how they are ultimately to be placed.

Placement of Transient Optical State Change Security Materials WithRespect to Optical Data Structures on the Optical Discs

[0073] In General

[0074] As disclosed in WO 02/03386 A2, the transient optical statechange security materials may be placed anywhere on or within theoptical medium so long the PUH can detect the change in optical state.Such security materials may advantageously be placed in or on theoptical medium on either the laser incident surface (“LI Method”) or thepit/land surface (a.k.a. the focal plane) of the optical medium (“FPMethod”). Advantageously, changes in reflectivity, absorbance, opticalclarity, and birefringence due to the application of the securitymaterials may be monitored to assure that such materials do notinterfere with industry standards, suggestive that the optical mediummight not adequately perform in its reader. Audio Development's CD-CATSand DVD-CATS testers may be used to measure servo responses, HF signalamplitudes, and error behaviors.

[0075] Surface Application

[0076] The transient optical state change security materials may beapplied topically to a surface of the optical medium or component of theoptical medium during manufacture. Topical surface application may be byany of the imprinting techniques known to those of ordinary skill in theart, including, but not limited, air brush, industrial ink jet printing,desktop ink jet printing, silkscreen printing, sponge/brush application,air brushing, gravure printing, offset lithography, oleophilic inkdeposition onto a wetted surface.

[0077] The material may also be spin coated. Spin coating a layercomprising the transient optical state change security materials may bea preferred method of application due to precision and uniformityrequirements. Only minor process modification are typically necessary toimplement in-line deposition by spin coating. The spin coat may beapplied using any means known to those of ordinary skill in the art. Forexample, a precise, small quantity of dye may be placed in a radial linewith the disc stationary and the disc subsequently spun to produce aprecisely coated area. Conventionally spin coating entails a first rampof acceleration to first speed, a first dwell time at first speed, asecond ramp of acceleration to second speed, a second dwell time atsecond speed, a third ramp of acceleration to third speed, a third dwelltime at the third speed, deceleration, and post conditioning(baking/drying/curing at defined temperatures for defined periods oftime) The spin profile may be advantageously controlled to produce thedesired coating. It is preferred that when such security materials areplaced on an otherwise exposed surface of the completed optical medium,that the security materials be coated to protect against wear of thesecurity material due to handling of the optical medium. Thus, forexample when security material is applied to the laser-incident surfaceof a completed optical disc, it is advantageous that a hard-coating beplaced over the security material to prevent wear or removal of thesecurity dye from such surface.

[0078] The transient optical state change security materials may becoated onto the pit-surface prior to lacquering of the optical medium,addition of a second substrate (DVD) and/or application of any label.The later addition of such materials helps protect against removal anddegradation of the security material. Any covering over the securitymaterial may further comprise a special filtering material, such as GEfiltering polycarbonate.

[0079] The transient optical state change security materials may beplaced at the pit/land surface.

[0080] In one embodiment, pit/land placement may makes use of pitgeometries needed to accommodate dye deposition at the focal plane ofthe disc. Techniques such as Atomic Force Microscopy (AFM) may be usedto verify dimensions. Optimal pit geometries for the particular securitymaterial may be determined by spin coating the material onto a surfacehaving variable pit depths, determining which pits contain the materialsas by, for example, microscopy, and determining which pit dimensionswhich may hold material after spin coating, actually allow for playbackwithout the dye in them, and without errors. The optical medium with thematerial and determined pit geometries is then checked to determinewhether a dual data state, error to valid, or valid to error, may beproduced. Different radii, depths etc. may be investigated.

[0081] For example, without any limitation, a variable pit depth glassmaster for a CD may be made using a 350 nm thick photoresist and LBR(laser bean recorder) power step series, as to form 13 steps in randomorder, except for nominal depth tracts which contain 50 MB ofpseudo-random user data, as follows: 160nm (nominal pit depth), 120 mn,150 nm, 180 nm, 160 nm (nominal), 210 nm, 240 nm, 270 nm, 160 nm(nominal), 300 nm, 320 nm, 350 nm, 160 nm (nominal). Similarly, avariable pit depth master for DVD may be made using a 200 nm thickphotoresist and LBR power step series, as to form 13 steps in randomorder except the nominal depth tracks, wherein each track contains 360MB of pseudo-random user data, as follows: 105 nm (nominal), 80 nm, 95nm, 110 mn, 105 nm (nominal), 125 nm, 140 nm, 155 nm, 105 nm, 170 nm,185 nm, 200 nm, 105 nm (nominal). The discs can be spun coat withmaterial comprising transient optical state change security material,the pit depths incorporating the material determined, and pits of suchdimensions analyzed for whether the impact upon read without thematerial when the optical medium is completed (metallized, lacqueredetc.)

[0082] Detection from the laser-read side may be enhanced by includingone or more deep pits in the substrate, such pits being made using amaster designed to form multiple-depth pits. Detection may also beimproved by optimizing pit geometry of the deep pits. Variable pit depthglass masters may be fabricated. For example, 350 nm thick photoresistsand LBR power step series may be employed to produce different stepsincluding nominal depth tracks for pseudo-random user data

[0083] The pits may advantageously be placed only in the outer 5 mm ofthe disc, or in the lead out region of the disc. In such case, only theouter portion of the disc, or lead out region, need be coated.

[0084] The deep pits may also be used to form an interferometer byplacement of the security material with respect to the deep pit prior tometallization.

Placement of Transient Optical State Change Security Material inPolycarbonate with Formation of Extended Pits Upon Molding Prior toMetallization to Form an Interferometer Along the Extended Pits

[0085] The transient optical state change security material mayincorporated into the polycarbonate and deep pits (bumps from the readside) flanking one or more lands molded into the polycarbonate atpredetermined locations. The pits may be constructed to be of such depththat as to form an interferometer between the enlarged bumps, whenviewed from the read side, that fail to reflect sufficiently for read bythe PUH of the optical reader when the security material changes statedue exposure to the incident read laser beam. This system thereforeemploys two components: the transient optical state change securitymaterial distributed throughout the polycarbonate, and a interferometer,of the Fabry-Perot type (“FPI”).

[0086] The FPI works by varying the amount of light reflected back to asource. This variation is dependent on the intensity, angle andwavelength of the light entering the interferometer. The physicalconstruction of an FPI, when viewed from the read-side, can beeffectuated during the stamping procedure by creating one or more pitsof extended depth flanking one or more lands. The glass masteradvantageously is modified to create such pits of extended depth. Thedeep pits act as the walls of the FPI, while the reflective land at thebottom acts as the primary reflective surface. By carefully selectingthe transient optical phase change security material, under one set ofconditions (intensity, wavelength, angle) there will be considerablereflectivity back to the source, while under a second set of conditions,there will be significantly less light reflected back to the source.These two states will be driven by the security material placed in thepolycarbonate (PC).

[0087] If the interferometer is appropriately manufactured, and thetransient optical state change security material chosen, the material inthe PC will be essentially transparent to the PUH and all data will beread at one state. During the read, the material will absorb energy.When enough energy has been absorbed by the material its transmittancewill decrease (less energy passes through) and it will cause a slightchange in refractive index. In the second state with the transmittancedecreased, if property designed, the input energy threshold for the FPIcan be made to be crossed, and very little signal will be reflected. Bycarefully selecting the security material and its concentration in thePC, one can cause enough signal to the optical data structures so as tobe able to read such data. One the other hand, if RI is changed when thematerial is activated by the read beam, the security material and itsconcentration, and the depths of the pits (from the non-read side)should be such as to result in a change in wavelength that crosses theFPI threshold resulting in a reduction in reflectivity, but thewavelength change should be small enough that normal sized optical datastructures may still be resolved. It should be noted that the disc mayhave to be preformatted, such as is the case with CD-RW, if theautomatic gain control (AGC) is inappropriately invoked based on ATIPinformation.

Placement of Transient Optical State Change Security Material BetweenSubstrates Comprising the Optical Medium

[0088] Dye may be deposited and encapsulated between substrates, forexample an ambient protective polycarbonate, such as that produced byGeneral Electric. Such placement eliminates optical hard coating, usesexisting manufacturing processes, provides protection, and expands thepossible dye chemistries that might be employed because read laseroptical power density is, for example, greater at 0.6 mm from the pitsurface than at 1.2 mm.

STATEMENT REGARDING PREFERRED EMBODIMENTS

[0089] While the invention has been described with respect to preferredembodiments, those skilled in the art will readily appreciate thatvarious changes and/or modifications can be made to the inventionwithout departing from the spirit or scope of the invention as definedby the appended claims. All documents cited herein are incorporated intheir entirety herein.

We claim:
 1. A method for fabricating an optical medium readable by an optical reader, said method comprising the steps of: (a) molding a substrate so as to have a first major surface with information pits and information lands thereon and a second major surface that is relatively planar; (b) applying a transient optical state change security material capable of converting from a first optical state to a second optical state upon exposure to the laser of said optical reader to at least a position of said first major surface; (c) applying a reflective material over the first major surface so as to cover said information pits and information lands; wherein the transient optical state change security material comprises:

where R₆, R₇, R₈, and R₉ are alkylamino and R₁, R₂, R₃, R₄ and R₅ are selected from the group consisting of hydrogen, alkyl, aryl, alkoxy, thioalkoxy, alkylamino, nitro, amino and halogen.
 2. The method of claim 1 wherein R₆, R₇, R₈, and R₉ are propyl or hexyl and R₁, R₂, R₃, R₄ and R₅ are hydrogen.
 3. An optical disc readable by an optical reader generating a reading beam comprising: a substrate having first major surface with one or more information pits and lands thereon, and a second major surface that is relatively planar, said information pits and lands convertible into digital data bits when read through the second major surface by said reading reading beam of said optical reader; a transient optical state change security material capable of existing in a first unactivated state and a second activated state on said first or second major surface, said transient optical state security material comprising:

where R₆, R₇, R₈, and R₉ are alkylamino and R₁, R₂, R₃, R₄ and R₅ are selected from the group consisting of hydrogen, alkyl, aryl, alkoxy, thioalkoxy, alkylamino, nitro, amino and halogen; and a reflective layer positioned over said information pits and lands; wherein in at least two or more of said pits flanking a land are of sufficient depth to form a light-reflecting interferometer when the transient optical state material is in its first state but not in its second state, upon interface with said reading beam.
 4. The optical disc of claim 3 wherein R₆, R₇, R₈, and R₉ are propyl or hexyl and R₁, R₂, R₃, R₄ and R₅ are hydrogen.
 5. The optical storage medium of claim 3 wherein said transient optical state change security material is opaque in its first optical state and translucent in its second optical state.
 6. The optical storage medium of claim 3 wherein said transient optical state change security material is translucent in its first optical state and opaque in its second optical state.
 7. An optical disc readable by an optical reader generating a reading beam comprising: a substrate having first major surface with one or more information pits and lands thereon, and a second major surface that is relatively planar, said information pits and lands convertible into digital data bits when read through the second major surface by said reading reading beam of said optical reader; a transient optical state change security material capable of existing in a first unactivated state and a second activated state, comprising:

where R₆, R₇, R₈, and R₉ are alkylamino and R₁, R₂, R₃, R₄ and R₅ are selected from the group consisting of hydrogen, alkyl, aryl, alkoxy, thioalkoxy, alkylamino, nitro, amino and halogen; wherein said transient optical state change security material being selectively applied along the first major surface so as to provide an erroneous digital data bit read when the transient state change security material is in its first unactivated state and its second activated state.
 8. The optical disc of claim 7 wherein R₆, R₇, R₈, and R₉ are propyl or hexyl and R₁, R₂, R₃, R₄ and R₅ are hydrogen.
 9. An optical medium comprising a compound of the following structure:

where R₆, R₇, R₈, and R₉ are alkylamino and R₁, R₂, R₃, R₄ and R₅ are selected from the group consisting of hydrogen, alkyl, aryl, alkoxy, thioalkoxy, alkylamino, nitro, amino and halogen; and wherein said compound is applied to an optical medium and is detectable on said optical medium by an optical reader producing a wavelength of from about 630 nm to about 660 nm by a transient change in optical state from an initial optical state to a second optical state.
 10. The optical medium of claim 9 wherein the compound is associated with an optical data deformation in a manner such that the read of the optical data deformation is different when the compound is in its initial optical state and its second optical state.
 12. A method for authenticating an optical medium having a number of data deformations thereon, said method comprising the steps of: (1) providing for a complementary data state onto a portion of said optical medium; (2) detecting said complementary data state on said portion of said optical medium. (3) authenticating said optical medium upon detection of said complementary data state on said pottion of said optical medium; wherein the complementary data state is produced using a transient optical state security material comprising:

where R₆, R₇, R₈, and R₉ are alkylamino and R₁, R₂, R₃, R₄ and R₅ are selected from the group consisting of hydrogen, alkyl, aryl, alkoxy, thioalkoxy, alkylamino, nitro, amino and halogen.
 13. The method of claim 12 wherein said complementary data state entails a change from one valid data state to a different valid data state.
 14. The method of claim 12 wherein said complementary data state entails a change from one erroneous data state to a different erroneous data state.
 15. The method of claim 12 wherein said complementary data state entails a change from a valid data state to an erroneous data state.
 16. The method of claim 12 wherein said complementary data state entails a change from an erroneous data state to a valid data state.
 17. The method of claim 12 wherein R₆, R₇, R₈, and R₉ are propyl or hexyl and R₁, R₂, R₃, R₄ and R₅ are hydrogen with respect to the transient optical state security material. 